Power tool for setting fasteners

ABSTRACT

A power tool including a motor at least partially located within the handle of the tool and having a first motor rotational axis extending along a longitudinal axis of the handle; and a fastener gripping portion operatively coupled to the motor via a transmission which in use causes movement of the fastener gripping portion along a second axis, between a home position and a retracted position to set a fastener engaged by the fastener gripping portion; the transmission including a bevel gear arrangement for redirecting torque to the second axis, and further including a mechanism for converting torque output from the bevel gear arrangement in use into a linear force for causing linear movement of the fastener gripping portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.18/153,043, filed Jan. 11, 2023, which claims priority from GB PatentApplication No. 2213921.6, filed Sep. 23, 2022, and GB PatentApplication No. 2202371.7, filed Feb. 22, 2022, the disclosures of whichis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This specification relates to a power tool for setting fasteners.

BACKGROUND OF THE INVENTION

Some existing blind rivet setting tools have a ball screw mechanismdriven by an electric motor for causing movement of a set of jaws inorder to pull the mandrel of a rivet. Such a tool is described inEP3530372A2 for example, wherein the motor is located above the handle.In order for the tool to feel balanced in a user's hand the manufacturerneeds to carefully consider the arrangement of features within thehousing relative to the handle. Having the motor and all transmissionfeatures above the handle makes the tool top heavy. Also due to spacelimitations within the housing there is some play off between arranginginternal features of the tool such that the tool works vs. arrangingsuch features so that weight distribution of the tool is optimised.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided apower tool comprising: a motor at least partially located within thehandle of the tool and having a motor output shaft extending along afirst axis extending along the length of the handle; and a fastenergripping portion operatively coupled to the motor via a transmissionwhich in use causes movement of the fastener gripping portion along asecond axis, perpendicular to the first axis, between a home positionand a retracted position to set a fastener engaged by the fastenergripping portion; the transmission comprising a bevel gear arrangementfor redirecting torque flowing along the first axis in use which isinput to the bevel gear arrangement so that torque output from the bevelgear arrangement flows along the second axis and wherein thetransmission further comprises a mechanism for converting torque outputfrom the bevel gear arrangement in use into a linear force for causinglinear movement of the fastener gripping portion.

The mechanism may be a ball screw mechanism extending along the secondaxis between the bevel gear arrangement and the fastener grippingportion. Alternatively, the mechanism may be a roller screw mechanismextending along the second axis between the bevel gear arrangement andthe fastener gripping portion.

The motor may be located entirely within the handle.

The transmission may comprise at least one planetary gear stage fortransferring torque from the motor along the first axis in use.

The at least one planetary gear stage may be at least partially locatedwithin the handle, optionally entirely located within the handle.

The power tool may comprise a battery attachment portion on the handlesuch that a notional line extending between the battery attachmentportion and the motor output shaft extends along the first axis.

The motor may be a brushless DC motor.

The fastener gripping portion may be a jaw assembly.

The power tool may be a blind rivet setting tool.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and embodiments of the invention will now be describedby way of non-limiting example with reference to the accompanyingdrawings, in which:

FIG. 1 shows a side cross-sectional view of a blind rivet setting tool.

FIG. 2 shows a close-up of part of the blind rivet setting tool in FIG.1 .

FIGS. 3 a and 3 b show a jaw assembly of the blind rivet setting tool inFIG. 1 in first and second configurations respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a side cross-sectional view of a blind rivet setting tool100. The tool 100 has a housing 102 of a clam shell type constructionhaving two halves which are fastened together. A battery 104 isreleasably connected to the base 122 of the handle 106 via a batteryattachment feature. To use the tool 100 a user inserts the mandrel of ablind rivet into a nose 108 of the tool 100 and pulls a trigger 110. Inresponse to a controller 112 of the tool determining that the trigger110 has been pulled the controller 112 generates a signal to activate amotor 114, which is a DC brushless motor. The motor 114 is located inthe handle 106 and has a motor output shaft 116. Torque from the motoroutput shaft 116 is transferred via a transmission 118 to a first bevelgear 120. The transmission 118 comprises at least one planetary geararrangement for reducing output speed while increasing torque.

The first bevel gear 120 rotates at a lower speed than the motor outputshaft 116 however with an increased torque relative to the motor outputshaft 116. The motor output shaft 116, transmission 118 and first bevelgear 120 are aligned along a first axis A-A which extends along alongitudinal length of the handle 106. By also locating the battery 104on the first longitudinal axis A-A weight distribution of the tool 100is improved.

It will be appreciated that there is some design freedom in thetransmission 118 between the motor output shaft 116 and the first bevelgear 120. In particular the number of planetary gear stages, and its (ortheir) configuration, forming the transmission 118 depends on therequired gear ratio to be achieved between the motor output shaft 116and the first bevel gear 120. Given that it is well known that planetarygear stages step down rotation speed while stepping up torque personsskilled in the art, based on the disclosure given herein, will be ableto decide upon a suitable transmission arrangement which achieves therequired gear ratio for their tool to function; wherein the appropriategear ratio depends on multiple factors including maximum achievablemotor output torque, pitch of the ball screw arrangement 130 describedbelow, friction between moveable features within the tool 100 and themaximum pull force required to set a fastener. It will be appreciatedthat for some tools 100 a suitable transmission 118 may only have asingle planetary gear stage, whereas for other tools a suitabletransmission 118 may have a plurality of planetary gear stages arrangedin series.

Continuing with reference to FIG. 1 a second bevel gear 124 is providedon the end face of a driving sleeve 126. The driving sleeve 126 isrotationally fixed relative to an input sleeve 128 of a ball screwarrangement 130. The driving sleeve 126 and input sleeve 128 are fixedrelative to each other due to a friction fit arrangement. An internalsurface of the input sleeve 128 comprises a threaded surface. The outersurface of the driving sleeve 126 is supported by bearings 132 whichenable rotation of the driving sleeve 126 with respect to the housing102. A threaded rod 134 is mounted within the input sleeve 128, whichextends through the input sleeve 128. A plurality of balls, such asmetal ball bearings, ride in the opposing threaded surfaces of the inputsleeve 128 and threaded rod 134, thereby defining a ball screwarrangement 130.

When the input sleeve 128 is rotatably driven by the driving sleeve 126this causes axial movement of the threaded rod 134. In other words,torque from the motor 114 is transferred through the transmission 118,first and second bevel gears 120, 124 and driving sleeve 126 to theinput sleeve 128, whereby rotation thereof causes axial movement of thethreaded rod 134. The threaded rod 134 is configured to move along asecond longitudinal axis B-B of the tool 100. The threaded rod 134 canmove forwards or backwards along the axis B-B depending on the motordriving direction.

Referring to FIG. 2 a connecting sleeve 300 is attached to a first end302 of the threaded rod 134, which is mounted to the threaded rod 134via a screw thread. A pull-back hull 304 is threadably attached to theconnecting sleeve 300. Axial movement of the threaded rod 134 along thesecond longitudinal axis B-B therefore also causes axial movement of thepull-back hull 304.

A jaw assembly 500 is located within the pull-back hull 304. The jawassembly (shown in FIG. 3 a ) has a plurality of circumferentiallyarranged jaws 306 each of which has a ramped outer surface 308 forcooperating with a conical inner surface 310 of the pull-back hull 304.A separator sleeve 312 is forced by a spring 314 against the jaws 306;more specifically a ramped front surface 316 of the separator sleeve 312is forced against ramped rear surfaces 318 of the jaws 306. A nosepiece320 is releasably attached at the opening to the nose 108 of the tool100 which has an annular ramped surface 402. Each of the jaws 306 have afront ramped surface 400 for cooperating with the annular ramped surface402 of the nose piece 320. Cooperation between the ramped outer surfaces308 of the jaws 306 and the conical inner surface 310 of the pull-backhull 304, between the ramped rear surfaces 318 of the jaws 306 and theramped front surface 316 of the separator sleeve 312 and between thefront ramped surfaces 400 of the jaws and the annular ramped surface 402of the nose piece 320 enables the tool 100 to set blind rivets in use.

To set a blind rivet, while the jaw assembly 500 is in a home position amandrel of the blind rivet is inserted through the nose piece 320 suchthat the mandrel extends between the jaws 306, thereby urging the jaws306 radially apart (see FIG. 3 b ). Upon pulling the trigger 110 of thetool 100 the controller 112 receives output from a trigger sensor and inresponse activates the motor 114 for causing the threaded rod 134, andthus the pull-back hull 304, to move along the second longitudinal axisB-B to the right in FIGS. 1 and 2 . As the pull-back hull 304 isretracted its conical inner surface 310 is forced against the outersurfaces 308 of the jaws 306, whereby a component of force draws thejaws 306 backwards with the pull-back hull 304 away from the homeposition whereas another component of force urges the jaws 306 radiallyinwards thereby clamping the mandrel of the blind rivet being setbetween the jaws 306.

In other words, pulling the pull-back hull 304 to the right in FIGS. 1and 2 causes the jaws 306 to grip and pull the mandrel of a rivet beingset. The blind rivet thus is pulled against the nose piece 320 fordeforming the blind rivet and when the mandrel of the blind rivet ispulled far enough for setting the blind rivet the mandrel snaps.

Designers are free to select a suitable way for the controller 112 tocontrol operation of the motor 114 in use to implement a fasteningoperation. In other words designers are free to select a suitable wayfor the controller 112 to determine when the jaw assembly 500 has beenretracted far enough during a fastener setting stage of operation atwhich point in time retraction of the jaw assembly 500 is ceased. Forexample a mechanical switch may be provided within the tool 100 and inresponse to the controller 112 determining that the trigger 110 has beenpulled by a user the controller 112 causes the pull-back hull 304 (andthus the jaw assembly 500) to be retracted until a feature of thepull-back hull 304 actuates the mechanical switch thereby generatingoutput indicative that the jaw assembly 500 has been pulled backsufficiently far to set a blind rivet. Alternatively, an optical sensormay be provided within the tool 100 which generates output based on thepresence or absence of a feature on the pull-back hull 304 wherein basedon output from the optical sensor the controller 112 can determine thatthe pull-back hull 304 (and thus the jaw assembly 500) has reached apredetermined retracted position for setting a blind rivet.Alternatively, the controller 112 may be configured to monitor themagnitude of current drawn from the battery 104 during a fasteningoperation and when the current draw drops by at least a predeterminedextent during a fastening stage of operation the controller 112 candetermine that the mandrel of the blind rivet being fastened has snappedand thus that the jaw assembly 500 has been pulled back sufficientlyfar.

Subsequently to the fastening stage of operation the tool 100 isrequired to perform a reset operation to dispose of the broken mandreland to accept a fresh blind rivet for setting. During a reset operationof the tool 100 the controller 112 causes the motor 114 to reverse itsdirection for moving the threaded rod 134, and thus the pull-back hull304, in the other direction along the second longitudinal axis B-B tothe left in FIGS. 1 and 2 . When the pull-back hull 304 has been movedsufficiently far to the left the spring 314 via the separator sleeve 312will urge the front ramped surfaces 400 of the jaws 306 against theannular ramped surface 402 of the nose piece 320. Further movement ofthe threaded rod 134 to the left in FIGS. 1 and 2 will increase thepressure of the spring 314 against the separator sleeve 312 and thuscause the front ramped surfaces 400 of the jaws 306 to ride along theannular ramped surface 402 of the nose piece 320 while the ramped rearsurfaces 318 of the jaws 306 ride along the ramped front surface 316 ofthe separator sleeve 312. This causes the jaws 306 to move radiallyoutwards and release the grip on the snapped mandrel, whereby withreference to FIG. 1 the released snapped mandrel can be caused to fallunder gravity along an internal path 204 in the direction of acollection chamber 200. For example, after a rivet setting operation,when the jaw assembly 500 has been returned to the home position, theuser tilts the tool 100 such that the snapped mandrel moves into thecollection chamber 200. The internal path 204 is defined by alignedopenings extending through components between the jaws 306 and thecollection chamber 200, including a first channel 202 extending throughthe threaded rod 134 along the second longitudinal axis B-B and a secondchannel 204 through a guidance sleeve 206.

Designers are free to select a suitable way for the controller 112 tocontrol operation of the motor 114 in use to implement a resetoperation. In other words designers are free to select a suitable wayfor the controller 112 to determine when the jaw assembly 500 hasreturned to the home position at which point in time reverse movement ofthe jaw assembly 500 is ceased. For example a mechanical switch may beprovided within the tool 100 and in response to the controller 112determining that the trigger 110 has been released by a user thecontroller 112 causes the pull-back hull 304 (and thus the jaw assembly500) to be moved in the reverse direction until a feature of thepull-back hull 304 actuates the mechanical switch thereby generatingoutput indicative that the jaw assembly 500 has returned to the homeposition. Alternatively, an optical sensor may be provided within thetool 100 which generates output based on the presence or absence of afeature on the pull-back hull 304 wherein based on output from theoptical sensor the controller 112 can determine that the pull-back hull304 (and thus the jaw assembly 500) has reached the home position.Alternatively, a magnet is provided on the pull-back hull 304 and a Hallsensor is provided in a fixed location within the tool, wherein suchfeatures can be arranged such that upon the Hall sensor generating asuitable output based on interacting with the magnet on the pull-backhull 304 the controller 112 can determine that the pull-back hull 304(and thus the jaw assembly 500) has reached the home position.

Turning to FIGS. 3 a and 3 b the jaw assembly 500 will now be discussedin more detail. FIG. 3 a shows a perspective view of the jaw assembly500 in a first configuration in which the jaws 306 are located radiallyas close to each other as possible. FIG. 3 b shows a perspective view ofthe jaw assembly 500 in a second configuration in which the jaws 306 areurged radially apart from each other such as by a mandrel of a blindrivet being inserted through the space between the jaws 306 or the jaws306 being forced against the annular ramped surface 402 of the nosepiece 320. The jaw assembly 500 comprises three identical jaws 306circumferentially arranged about a jaw assembly axis G-G. When the jawassembly 500 is mounted in the tool 100, the jaw assembly axis G-G iscoaxial with the second longitudinal axis B-B of the tool 100. The threejaws 306 can move radially with respect to the jaw assembly axis G-G.

There are situations during which the jaw assembly 500 is removed fromthe tool, in particular during routine maintenance of the tool 100during which it is disassembled and then reassembled after beingcleaned. Alternatively, the jaw assembly 500 may be swapped with a newjaw assembly because the jaws 306 of the original jaw assembly haveworn. Further alternatively the jaw assembly 500 may be swapped with anew jaw assembly because the different jaw assemblies are configured foruse with different sized mandrels. Referring again to FIGS. 3 a and 3 bthe jaw assembly has a flexible o-ring 502 for holding the jaws 306 ofthe jaw assembly 500 together when it is not located within the tool100. Each of the jaws 306 defines part of an annual groove 504 when thejaws 306 are in the configuration shown in FIG. 3 a wherein the o-ring502 is located in the annular groove 504 and biases the jaws 306together. The o-ring 502 can be made from an elastic material such asrubber.

In view of the foregoing, it will be appreciated that by locating themotor 114, the transmission 118 and the battery 104 on the same axis A-Aextending along the length of the handle 106 improves weightdistribution of internal features of the tool 100. Also, by providingthe motor 114 within the handle 106 leaves more space available withinthe tool housing above the handle, whereby there is more freedom toposition features of the tool in positions which improve weightdistribution of internal features of the tool.

By providing the motor 114 only partially within the handle 106 achievesthe abovementioned advantages to a lesser extent. By providing the motor114 and also at least part of the transmission 118 within the handle 106achieves the abovementioned advantages to a greater extent.

It will be appreciated that whilst various aspects and embodiments haveheretofore been described the scope of the present invention is notlimited thereto and instead extends to encompass all arrangements, andmodifications and alterations thereto, which fall within the spirit andscope of the appended claims.

In some embodiments the motor 114 is only partially received within thehandle 114.

In some embodiments at least one planetary gear stage of thetransmission 118 is received in the handle 106.

In some embodiments the motor 114 and the transmission 118 are receivedin the handle 106.

In some examples the battery 104 is removable from the tool 100 oralternatively the battery 104 is integral to the tool 100.Alternatively, or additionally the tool 100 may comprise other powersources e.g. it may be configured to receive power from a mains powersupply.

As shown in FIG. 1 , the driving sleeve 126 and input sleeve 128 arefixed to each other due to a friction fit arrangement. Alternatively,the driving sleeve 126 and input sleeve 128 can be fixed via aninterlocking arrangement such as a spline fit arrangement or other maleand female interlocking-type arrangement.

As shown in FIG. 3 a , the o-ring 502 is seated in a groove 504. In somealternative examples the o-ring 502 may be replaced with any suitablemeans to keep the jaws 306 together such as a c-clip, a circlip, an eclip, a snap ring, or another spring fastener.

The o-ring 502 is made from an elastic material such as rubber. In otherexamples, the o-ring 502 is optionally made from polyurethane, PTFE,ethylene propylene rubber, neoprene, nitrile, or silicone.

As shown in FIG. 3 a the jaw assembly 500 comprises three jaws 306.However, in alternative examples, the jaw assembly 500 can comprise anynumber of jaws 306 more than two.

In some examples the jaws 306 do not interlock with each other formaintaining jaw alignment.

In some embodiments the tool 100 can be configured to detect theoccurrence of a mandrel snapping by monitoring motor speed. During apull back stage of operation as the jaw assembly 500 pulls the mandrelof a rivet more tightly the speed of the motor 114 will decrease andthen suddenly increase when the mandrel snaps. The controller 112 canmonitor for such a sudden increase in motor speed and in response todetecting such occurrence determine that the mandrel of the rivet beingset has snapped and in response cease retracting the jaw assembly 500.Subsequently the controller 112 initiates the reset stage of operationeither automatically or in response to release of the trigger 110.

The motor 114 has been described as being a brushless motor and thecontroller 112 cooperates with the brushless motor (in particular withits control electronics) in order to control the brushless motor. Inother embodiments however the motor 114 may be a brushed motor having amotor output shaft driven by a stator and having at least one magnet onthe motor output shaft. It is here mentioned that in battery operatedembodiments the motor 114 is configured to operate using DC current,whereas in mains operated embodiments the motor is configured to operateusing AC current.

In some embodiments the tool 100 may have a roller screw mechanisminstead of a ball screw arrangement 300 for transferring rotationalmotion into linear motion. A person skilled in the art will appreciatethat this can be achieved by rotationally fixing the driving sleeve 126to an input sleeve of the roller screw mechanism; wherein a set ofrollers are provided between the internal surface of the input sleeveand an external surface of the threaded rod 134. When the driving sleeve126 is caused to rotate it drives rotation of the input sleeve of theroller screw mechanism and thus via the rollers causes linear movementof the threaded rod 134 and thus the jaw assembly.

Finally the heretofore described functionality need not necessarily beused exclusively in blind rivet setting tools but may be used in otherpower tools having a fastener gripping portion which moves backwardsfrom a home position in order to set a fastener and which is thenreturned to the home position. For example the heretofore describedfunctionality can be implemented in other tools such as rivet settingtools (not necessarily blind rivet fastening tools), swage fastenertools and lockbolt fastener tools wherein the fastener gripping portionof such tools is configured to grip the type of fastener which the toolis used to set e.g. the fastener gripping portion of a swage fastenertool is configured to grip a swage fastener.

What is claimed is:
 1. A power tool comprising: a motor at leastpartially located within the handle of the tool and having a first motorrotational axis extending along a longitudinal axis of the handle; and afastener gripping portion, the fastener gripping portion translatablealong a second central gripping axis and the fastener gripping portionoperatively coupled to the motor via a transmission, the transmissionincluding a bevel gear and a screw-nut force converter, the screw-nutforce converter including a translational screw and a rotational nut,wherein torque generated by the motor about the first rotational axis istransferred to the bevel gear which redirects the torque to apply arotational force to the nut about the second axis, the screw-nut forceconverter converting rotation of the nut into translation of the screw,wherein the fastener gripping portion is connected to the screw tocauses translational movement of the fastener gripping portion along thesecond axis, between a home position and a retracted position to set afastener engaged by the fastener gripping portion.
 2. The power tool ofclaim 1, wherein the second axis is perpendicular to the first axis. 3.The power tool of claim 1, wherein the screw-nut force converter is aroller screw mechanism extending along the second axis between the bevelgear arrangement and the fastener gripping portion.
 4. The power tool ofclaim 1, wherein the motor is located entirely within the handle.
 5. Thepower tool of claim 1, wherein the transmission comprises at least oneplanetary gear stage for transferring torque from the motor along thefirst axis in use.
 6. The power tool of claim 5, wherein the at leastone planetary gear stage is at least partially located within thehandle.
 7. The power tool of claim 6, wherein the at least one planetarygear stage is entirely located within the handle.
 8. The power tool ofclaim 1, further comprising a battery attachment portion on the handlesuch that a notional line extending between the battery attachmentportion and the motor output shaft extends along the first axis.
 9. Thepower tool of claim 1, wherein the motor is a brushless DC motor. 10.The power tool of claim 1, wherein the fastener gripping portion is ajaw assembly.
 11. The power tool of claim 1, wherein the power tool is ablind rivet setting tool.
 12. The power tool of claim 1, wherein thescrew-nut force converter is a ball screw mechanism extending along thesecond axis between the bevel gear arrangement and the fastener grippingportion.